From 46c6f1776e2f53eebb1fc361946877bab7533227 Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 13 Sep 2012 15:17:32 +0100 Subject: [PATCH] KEYS: Asymmetric key pluggable data parsers The instantiation data passed to the asymmetric key type are expected to be formatted in some way, and there are several possible standard ways to format the data. The two obvious standards are OpenPGP keys and X.509 certificates. The latter is especially useful when dealing with UEFI, and the former might be useful when dealing with, say, eCryptfs. Further, it might be desirable to provide formatted blobs that indicate hardware is to be accessed to retrieve the keys or that the keys live unretrievably in a hardware store, but that the keys can be used by means of the hardware. From userspace, the keys can be loaded using the keyctl command, for example, an X.509 binary certificate: keyctl padd asymmetric foo @s Signed-off-by: Rusty Russell --- crypto/asymmetric_keys/asymmetric_type.c | 120 ++++++++++++++++++++++- include/keys/asymmetric-parser.h | 37 +++++++ 2 files changed, 156 insertions(+), 1 deletion(-) create mode 100644 include/keys/asymmetric-parser.h diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c index bfb0424026aa..cf807654d221 100644 --- a/crypto/asymmetric_keys/asymmetric_type.c +++ b/crypto/asymmetric_keys/asymmetric_type.c @@ -11,6 +11,7 @@ * 2 of the Licence, or (at your option) any later version. */ #include +#include #include #include #include @@ -18,6 +19,9 @@ MODULE_LICENSE("GPL"); +static LIST_HEAD(asymmetric_key_parsers); +static DECLARE_RWSEM(asymmetric_key_parsers_sem); + /* * Match asymmetric keys on (part of) their name * We have some shorthand methods for matching keys. We allow: @@ -106,13 +110,80 @@ static void asymmetric_key_describe(const struct key *key, struct seq_file *m) } } +/* + * Preparse a asymmetric payload to get format the contents appropriately for the + * internal payload to cut down on the number of scans of the data performed. + * + * We also generate a proposed description from the contents of the key that + * can be used to name the key if the user doesn't want to provide one. + */ +static int asymmetric_key_preparse(struct key_preparsed_payload *prep) +{ + struct asymmetric_key_parser *parser; + int ret; + + pr_devel("==>%s()\n", __func__); + + if (prep->datalen == 0) + return -EINVAL; + + down_read(&asymmetric_key_parsers_sem); + + ret = -EBADMSG; + list_for_each_entry(parser, &asymmetric_key_parsers, link) { + pr_debug("Trying parser '%s'\n", parser->name); + + ret = parser->parse(prep); + if (ret != -EBADMSG) { + pr_debug("Parser recognised the format (ret %d)\n", + ret); + break; + } + } + + up_read(&asymmetric_key_parsers_sem); + pr_devel("<==%s() = %d\n", __func__, ret); + return ret; +} + +/* + * Clean up the preparse data + */ +static void asymmetric_key_free_preparse(struct key_preparsed_payload *prep) +{ + struct asymmetric_key_subtype *subtype = prep->type_data[0]; + + pr_devel("==>%s()\n", __func__); + + if (subtype) { + subtype->destroy(prep->payload); + module_put(subtype->owner); + } + kfree(prep->type_data[1]); + kfree(prep->description); +} + /* * Instantiate a asymmetric_key defined key. The key was preparsed, so we just * have to transfer the data here. */ static int asymmetric_key_instantiate(struct key *key, struct key_preparsed_payload *prep) { - return -EOPNOTSUPP; + int ret; + + pr_devel("==>%s()\n", __func__); + + ret = key_payload_reserve(key, prep->quotalen); + if (ret == 0) { + key->type_data.p[0] = prep->type_data[0]; + key->type_data.p[1] = prep->type_data[1]; + key->payload.data = prep->payload; + prep->type_data[0] = NULL; + prep->type_data[1] = NULL; + prep->payload = NULL; + } + pr_devel("<==%s() = %d\n", __func__, ret); + return ret; } /* @@ -132,6 +203,8 @@ static void asymmetric_key_destroy(struct key *key) struct key_type key_type_asymmetric = { .name = "asymmetric", + .preparse = asymmetric_key_preparse, + .free_preparse = asymmetric_key_free_preparse, .instantiate = asymmetric_key_instantiate, .match = asymmetric_key_match, .destroy = asymmetric_key_destroy, @@ -139,6 +212,51 @@ struct key_type key_type_asymmetric = { }; EXPORT_SYMBOL_GPL(key_type_asymmetric); +/** + * register_asymmetric_key_parser - Register a asymmetric key blob parser + * @parser: The parser to register + */ +int register_asymmetric_key_parser(struct asymmetric_key_parser *parser) +{ + struct asymmetric_key_parser *cursor; + int ret; + + down_write(&asymmetric_key_parsers_sem); + + list_for_each_entry(cursor, &asymmetric_key_parsers, link) { + if (strcmp(cursor->name, parser->name) == 0) { + pr_err("Asymmetric key parser '%s' already registered\n", + parser->name); + ret = -EEXIST; + goto out; + } + } + + list_add_tail(&parser->link, &asymmetric_key_parsers); + + pr_notice("Asymmetric key parser '%s' registered\n", parser->name); + ret = 0; + +out: + up_write(&asymmetric_key_parsers_sem); + return ret; +} +EXPORT_SYMBOL_GPL(register_asymmetric_key_parser); + +/** + * unregister_asymmetric_key_parser - Unregister a asymmetric key blob parser + * @parser: The parser to unregister + */ +void unregister_asymmetric_key_parser(struct asymmetric_key_parser *parser) +{ + down_write(&asymmetric_key_parsers_sem); + list_del(&parser->link); + up_write(&asymmetric_key_parsers_sem); + + pr_notice("Asymmetric key parser '%s' unregistered\n", parser->name); +} +EXPORT_SYMBOL_GPL(unregister_asymmetric_key_parser); + /* * Module stuff */ diff --git a/include/keys/asymmetric-parser.h b/include/keys/asymmetric-parser.h new file mode 100644 index 000000000000..09b3b4807f5c --- /dev/null +++ b/include/keys/asymmetric-parser.h @@ -0,0 +1,37 @@ +/* Asymmetric public-key cryptography data parser + * + * See Documentation/crypto/asymmetric-keys.txt + * + * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#ifndef _KEYS_ASYMMETRIC_PARSER_H +#define _KEYS_ASYMMETRIC_PARSER_H + +/* + * Key data parser. Called during key instantiation. + */ +struct asymmetric_key_parser { + struct list_head link; + struct module *owner; + const char *name; + + /* Attempt to parse a key from the data blob passed to add_key() or + * keyctl_instantiate(). Should also generate a proposed description + * that the caller can optionally use for the key. + * + * Return EBADMSG if not recognised. + */ + int (*parse)(struct key_preparsed_payload *prep); +}; + +extern int register_asymmetric_key_parser(struct asymmetric_key_parser *); +extern void unregister_asymmetric_key_parser(struct asymmetric_key_parser *); + +#endif /* _KEYS_ASYMMETRIC_PARSER_H */